With octanol-water distribution coefficients38,39. Vapor Stress Osmometry Studies Interactions of urea using the modestly soluble disodium salts of the 5′-NMPs had been quantified from VPO measurements by determining the osmolality difference Osm (Eq. 4) as a function of m2m3, the item with the 5′-NMP and urea molalities (Figure two). Linear regression with the data in Figure 3 with intercepts fixed at zero yields values of 23/RT (Eq. 4) summarized in Table 1. The negative slopes in Figure two indicate a net favorable preferential interaction of urea with all the 5′-NMP anion and the two Na+ ions. Interpreting Preferential Interactions (23/RT values) Among Urea and Nucleic Acids Values of 23/RT for interactions between urea and nucleobases/base analogs/nucleosides/ nucleotides obtained in the slopes of plots of VPO and partitioning data (Figs two and three) are summarized in Table 1.1003575-43-6 Purity The groups in Table 1 (nucleobases, nucleosides, mononucleotides) are arranged in order of escalating molecular weight and ASA (Table S1). Since interactions of urea with all but one style of organic surface investigated to date (the exception becoming cationic N)4 are favorable, we expect urea to possess a more favorable interaction (extra adverse 23/RT worth) with bigger compounds. Indeed, uridine, deoxythymidine and adenosine 23/RT values are much more favorable (extra negative) than uracil, thymine and adenine 23/RT values by around 0.1 m-1, presumably due to a favorable interaction using the sugar ASA on nucleosides. On the other hand, urea exhibits significantly less favorable interactions together with the 5′-NMP disodium salts than with corresponding nucleobases and nucleosides. This is constant with the powerful unfavorable interaction of urea with Na+ ions deduced from model compound data4 (2Na+ = 0.197 ?0.028 m-1). Correction for this impact shows that 23/RT values for interactions of urea with the 5′-UMP dianion (-0.363 ?0.057 m-1) and 5′-dTMP dianion (-0.345 ?0.031 m-1) are far more negative than for the nucleosides uridine (-0.31 ?0.02 m-1) and deoxythymidine (-0.31 ?0.02 m-1). Although the 23/RT worth calculated for the 5′-AMP dianion (-0.323 ?0.030 m-1) is much less adverse than for the nucleoside adenosine (-0.35 ?0.02 m-1 ), both are a lot more negative than 23/RT for the nucleobase adenine (-0.581063-34-5 Purity 27 m-1 ?0.PMID:33426698 01). Qualitative analysis of these 23/RT values leads to the following image from the preferential interactions of urea with nucleic acid base, sugar, and phosphate functional groups: 1. Values of 23/RT for nucleobases, base analog, nucleosides, and Na2NMPs are all adverse, displaying that preferential interactions of urea with all model compoundsNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptJ Am Chem Soc. Author manuscript; accessible in PMC 2014 April 17.Guinn et al.Pagestudied are favorable. For that reason, urea must interact favorably with most if not all kinds of nucleic acid surface. two. Values of 23/RT for purine and pyrimidine bases and base analogs with equivalent functional groups (e.g. adenine vs. cytosine, 5′-AMP vs. 5′-CMP or hypoxanthine vs. uracil) reveal a far more favorable 23/RT from the purines (with two fused heterocyclic aromatic rings) than the pyrimidines (with 1 heterocyclic aromatic ring), indicating a favorable interaction of urea with ring surface. Values of 23/RT for the nucleic acid bases adenine, thymine and uracil are much less damaging (much less favorable) than the corresponding values for the nucleosides adenosine, thymidine, guanosine and uridine, indicating that urea has a.